The present invention concerns the production of jacquard-patterned pile knits--such as carpets, upholstery, fur imitations, and the like--on warp-knitting machines of the type comprising two needle-rows. In this type of warp-knitting machine and technique, each of the two needle-rows is fed a large number of knitting threads for production of the two ground fabrics of a double pile fabric, and those pile threads which are to pattern are engaged by the hooks of the two needle-rows in alternation and are tied into respective ones of the two ground fabrics of the double pile warp knit in the form of half loops, whereas those pile threads which are, at any given time, not to appear in the visible pile pattern are kept out of the operative range of the needle hooks in order that they not be thusly tied into the ground fabric.
This is the type of warp-knitting machine and technique to which the present invention relates. Machines and methods of somewhat comparable type are also known, and warrant mention here.
Thus, Federal Republic of Germany Pat. No. DE 55821 discloses a pile-knitting machine having two needle bars, whose rows are arranged almost parallel to each other, with first one needle-row being driven out to yarn-taking position, and then the other, i.e., in alternation. Associated with each of the two needle-rows is a respective one of two rows of eyelet needles which feed to the needles of the associated needle-row the knitting threads to be used for formation of the ground fabric. Arranged above each two corresponding and oppositely located needles of the two needle-rows is one respective pile-thread guider of a row of such pile-thread guiders which extends along the length of the two needle-rows. The pile-thread guiders can be raised and lowered individually and are controlled by a jacquard system. The row of pile-thread guiders swings, as a unit, through the two needle-rows. If a particular pile thread is, at a particular time, not to appear in the visible pile pattern, it is lifted up by its associated pile-thread guider in such a way that, when this thread is in the general operative vicinity of one needle-row it not be caught by a hook of that needle-row. The pile thread which is not to appear in the visible pattern (hereafter called a "non-patterning" pile thread) is tied into one of the two ground associated with the other needle-row in accordance with fringe technique.
The disadvantage of this type of prior-art pile-knitting machine is that it is, accordingly, not possible to freely knit jacquard color patterns. Even if, instead of the single row of pile-thread guiders, use were made of a plurality of such pile-thread guider rows, with all the pile-thread guiders of such plural pile-thread guider rows individually controllable, jacquard color patterns could be achieved with only an unacceptable degree of quality. This is because it is not possible to move sets of bulked pile threads through the interneedle gaps of the needle-rows at high speed, if resort is to be had only to ordinary guidance techniques. Also, the tying-in of non-patterning pile threads in the form of full loops is extremely disadvantageous with respect to the rate of consumption of pile thread. Furthermore, the ground fabric of the piled knit, which is produced in accordance with elementary tricot technique, tends to be elastic and insufficiently shape-retentive, making it unsuitable, for example, for carpets.
For these reasons, until now jacquard-patterned pile knits have in general been produced only on warp-knitting machines having one needle bar and utilizing pile sinkers, pegs or grippers for the pile loops, such as disclosed, for example, in German Republic Pat. Nos. DD 110 073, DD 119 275, and DD 20 006.
However, with these warp-knitting machines, all those pile threads which are not to pattern are tied into their associated wale in the form of vertical stuffer. The rate of pile-thread consumption is accordingly high, i.e., higher than would be needed if one used a double-fabric carpet-weaving machine of the type capable of producing substantially the same patterned pile fabric.